Sirius is the brightest star in our night sky and is ideal for spectral analysis due to its slow rotation and lack of atmospheric convection. Its mass, radius, surface gravity, and effective temperature have all been constrained to better than 1%. In 1979 Kurucz and Furenlid published the Sample Spectral Atlas for Sirius, which identified most spectral absorption lines between the wavelengths 354 nm and 440 nm. However, there are prominent spectral lines from O, Na, Mg, Si, Ca, Cr, Fe, and Zn that lie outside of this range that are important for abundance analyses. To expand the wavelength range, we constructed an atlas using spectral data from the Very Large Telescope Ultraviolet Echelle Spectrograph (VLT/UVES) from 305 nm to 850 nm for comparison with a non-local thermal equilibrium (NLTE) stellar atmosphere model for Sirius.
This poster presents sample pages from the atlas and an assessment of the quality of the match between the model spectrum and the VLT/UVES data.
We identified 112 spectral lines from singly and/or doubly ionized species of the elements O, Mg, Si, V, Cr, Fe, Ni, La, Pr, and Lu, which are not well matched to the model. The data and model lines in some regions of our spectrum did not properly match up with each other, either being too weak or strong, or some absorption lines could be missing entirely. However, there are hundreds of other well-fitting spectral lines. We anticipate that our methods of spectral examination will be applicable for the construction of atlases for other stars.